166 NOTES ON THE SALMO SALAR SPECIMEN — MORROW. 



very short spinous processes lying in front of their articulation 

 with their centrum. 



C. 28. The 26th pair of ribs have spinous processes about £ of an 

 inch in length, to which they are attached and pass posteriorly 

 to their articulation. 



•Q. 29. The 27th pair are united by cartilage to the end of, and 

 behind spinous processes Jan inch in length on the 29th centrum, 

 their ends do not reach the centrum but are attached posteriorly 

 to the sp. processes. This pair are not so flat as their preceding- 

 ribs. 



G. 30. The 28th pair. The spinous processes to which this pair 

 are attached are f of an inch in length, and their attachment 

 rather more than a quarter of an inch. 



C. 31, The 29th pair are attached posteriorly to strong sp. pro- 

 cesses f of an inch in length, which are united transversely form- 

 ing the first bsemal arch. 



G. 32. The 30th pair. Their spinous processes are also about | of 

 an inch in length to which the attachment of the ribs is about 

 f of an inch. 



G. 33. 31st pair of ribs \ have sp. processes f and ]% of an inch 

 C. 34-. 32nd do. J in length, and have short attachments 



to their processes. 



C. 35. On this centrum (the last of the abdominal centra), at- 

 tached to spinous processes, which are united at their ventral 

 ends, are the 33rd and last pair of ribs. A hasty examination of 

 this specimen might lead me to say that it has only 32 pairs of 

 ribs ; but the dorsal ends of the 33rd pair are attached closely 

 together and to the narrow point of their sp. processes, and are 

 anchylosed. The examination of younger fish makes this cer- 

 tain. This pair of united ribs forms the support of the anterior 

 interspinous fin bone of the anal fin, which in this case it over- 

 lapped, and was attached on the right hand side about f of an 

 inch.* 



The ventral ends of the last five or six pairs of ribs gradually 

 approach each other until they touch in the last or 33rd pair, 



*The sp. processes on the 29th, to and including the 33rd and last pair of rihs, are transversely 

 united, making five abdominal haemal arches. 



